Mexico lies just south of the U.S
Mexico (capital: Mexico City)
Mexico is the closest country south of the US, as it borders the US to the south.
Mexico is the bordering nation that is south of the US. However, other nations are also just south of the US, though not by land borders. For example, Cuba.
Mexico is the country located south of the us
There is no country below the US, however Mexico borders it to the south
The US is bordered to the south by Mexico.
The US is bordered to the south by Mexico.
Mexico is the country on the southern border of the US
mexico
It sounds like you're talking about Mexico.
Mexico is the only country south of the western United States.